Minimizing Current Distortion of a Three-Phase Bridge Rectifier Based on Line Injection Technique

This paper demonstrates a new concept and a novel passive resonant construction, which is connected between the ac and dc sides of the three-phase bridge rectifier, for reducing line current harmonics. This resonant net connection, in combination with the conduction intervals of each diode, generates a circulating third harmonic current between the ac and dc sides of the diode rectifier. This will cause a significant reduction in line current harmonics. As a result of this, the shape of line current becomes nearly sinusoidal. Results of analytical, simulation, and experimental verification on a typical example are presented. The total harmonic distortion (THD) of the line current can be reduced from 32% to 5%. Therefore, based on this concept a very cheap, lossless, and passive rectifier with low THD and almost unity power factor has been developed